There is a constant demand for improved materials, especially for aerospace applications. One area for which improved materials are sought is structural materials having a high strength to weight ratio and/or a high stiffness to weight ratio.
Fiber materials which have exceptional combinations of strength and modulus are commercially available. Practical use of such fibrous materials can be made by embedding the fibers in a matrix which can transmit stress so that a bulk article having properties derived in part from the fiber materials can be produced.
High performance fibers produced to date have included graphite, silicon carbide, and boron. Fibers of these classes coated with other materials such as graphite, boron and boron carbides are also available.
Titanium is a natural candidate for a matrix material suited for use at high temperatures and having good inherent properties, Unfortunately, titanium alloy-fiber combinations used heretofore have been generally unsuccessful because the prior titanium alloys have had significant solid solubility for the fiber materials. This solid solubility characteristic is detrimental to the composite material since during high temperature fabrication and/or use of the resultant composite interdiffusion occurs between the matrix and the fiber, forming an intermediate zone of a brittle titanium intermetallic compound. A continuous brittle layer between the fiber and the composite is highly detrimental to the composite properties.
U.S. Pat. No. 4,499,156 which issued in Feb. 12, 1985 describes a typical prior art titanium-fiber composite material.
It is an object of the present invention to provide improved titanium matrix composites. It is another object of this invention to provide an improved method for fabricating titanium matrix composites. Other objects, aspects and advantages of the present invention will be apparent to those skilled in the art from consideration from the following description of the invention and the attached claims. In what follows, percent values are weight percent unless otherwise noted.